I recently started doing no-sparge batches, and had to shift to my 150 quart cooler to be able to hold the entire grain bill plus all the water to make my pre-boil volume.
For a thirty pound grist, the grain bed depth was 4 inches. I ran off 15 gallons of wort in 15 minutes, and it ran very clear after vorlauf.
I have no frame of reference for what are normal run-off times when doing no-sparge and batch sparges.
Can anyone elaborate for me? Denny, surely you know by heart how long to expect a batch to run off based on volume going to the kettle.
My guess is that so long as its not a stuck mash, grain bed depth has no effect on run-off speed for batch sparging.
Based on my current knowledge, the OP would do well to set up his rectangular cooler as a mash tun. It can't hurt to have both available, and as posted by others, it's a simple and cheap thing to do.